Drafting instrument



1932- c. F. GOLDEN DRAFTING INSTRUMENT Filed Feb. 1. 1950 Patented Aug. 2, 1 932 I p 5 v v DRAFTTIHGQINSTRUMENTIIT i Application filed rbruary'l, 1930. "Serial Na i-25,329.

This invention relates to a drafting insti'u l ment, one of its objects being'to provide a light, simple and compact instrument'of this character which can be used accurately 'asa protractor, compass, T-square and Vernier scale.

Another object is to provide an instrument" formed of few parts including a protractor' head and. an arm which are detachably connected so that one can be used independently of the other. v

A further object is to pro'videa protractor head with a pivot pin located at thecenter of the base line and in line with one edge 1-5 of the arm, this pin being shiftable ,to en-' gage the surface on which theinstrument is mounted. With the foregoing and other objects in view which will appear as the description proceeds,'theinvention resides in the combination and arrangement of parts'and in I the details of constructionhereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without de-,

parting from the spirit of the invention.

In the accompanying drawing the" preferred form of the invention has been shown.

In said drawing,

Figure l is a plan view of the instrument.

Figure 2 is a section on line 22, Fig- Referring to the figures by characters of reference, 1 designates a semi-circular pro tractor head the arcuate outer edge of which is graduated to indicate degrees and fractions of degrees of a circle. The central graduation is indicated by the zero character 0, as shown at 2.

The straight edge 3 of the protractor head is graduated preferably in inchesand fraccenter thereof and the center port on of this tions thereof in opposite directions from the v rams-a CHARLES FQGOLDENfOF Dams-alumna I edge iscut away to provide a clearance indi-l f cated at 4; The outer edge portions of the;

headl are'pressed downwardlyby beveling i the head so that said headfcan on-a supporting surface. I V Fitted snuglybeneath the head 1 at90 to thus lie flat itsstraight edge 3. is a'fla't tongue 5 projecting fromone end of an e'nlongated vernierar n 6. The longitudinal edge portionsof the I arm are inclined downwardly so as to lie in the same planewith the edges of the'head' l,

These edges of the arm are graduatedto indi cate desired units'of "linealjmeasure and any desired fractions thereof; The graduations are designated by numerals 'or the like as shown, for example, in-Figure 1.

7 That end of the arm-e which is 'ofi'setand flattened to produce the tongue 5 is 'seatedgin,

a recess 7 formedin head 1 alongthe straight edge 3 and at one side of the cut-away; portion or clearance 4. i f f Secured to the tongue 5 are screw threaded studs 8 which extend-through openings 9 in v head 1 are engaged "by clamping nuts lQ which serve to bearfonthehead and-hold tonguefila-nd arm 6 fixed relativeto the head. Secured onthe head 1 atone side of the clearance 4 is a small base plate 11' from which projects 13. The bore 14 in'this" sleeve'l1a's a pin '16 'slidabl'y mounted therein provided with-a head 17 at one'jend. 'A-portion of the pin is reduced annularly as at 15 to'rec'eivea set I an upwardly extending bracket or arm 12 carrying an integral sleeve screw18; Acenteringpoint18eXtendsfrom that end'of the pinremote from-the head 17;

I The outer or free end of arm6 is obliquely v f disposed as indicated at '20;and 'isprovided with suitable graduationsjfor designating fractions of a degree in'mlinutes-orotherwise.

One longitudinal' edge of the arm is in ali'nementor substantial alinenient with thezjero graduation 2 and the point 19.. I'nf practice it has been found desirable'to{setback the longitudinal edge of the arm adistan'ce equal to the thicknessof a fine pencil point 'sothat 1 a line drawn along said edge will aline with the-point19,-and'theZero graduation 2.

/ It willkbe obvious that, by removing- 1 511 j nuts :10, studs, 8 can" be withdrawn 1 front the other.

"head 1 and it is thereby possibleto use the the arm 6 independently of each head and 'As has heretofore been stated this instrument can be used as a protractor, compass,

T-s quare and vernierscale. Attention is directed to the novel arrangement of gradua-i 1 tions on the protractor',head; The outer series of graduations is aranged to aid in reading angles ranging from to,90 east or west,north or south, and'to facilitatemeasurement of the segments of circles. F or ex sample, should, it be desired to, lay out an' azimuth of350 it would be necessary first to anchor the'pin 16 at the desired position'on the base line-with the arm 6 pointing north parallel to the base l ne. The 0 graduation Wlll thus'be in position on the line. The

vprotract or' head is then rotated in a clockwise direction as indicated by thearrow until assured to the user of th s instrument.

When theparts are assembledas shown in Figure '1 the pivot pin becomes useful when.

the device is employed asa T-square, it being possible readily to swing the instrument about the pivotalpoint.

The protractor feature of the instrument is important. For example, should it be de- I sired to produce an angle north 600vv ft., 45 degrees minutes east, the pivot point is positioned on the base line.v -The zero degree 2 at the south meridian is positioned inllne with the edge of arm 6. The instrument isthen swung about the pivot until the arm reachesa point which will cause the graduation to appear at the southmeridian A mark ismade at the first graduation on the outer end 20' of the arm 6. The armis' then 7 turned until its straight edge coincides with r the last mark made. A line is then drawn drawing the set screw along the straightedge tothe center.

By providing a set screw 18 which projects 7 into groovelti in pin 16 the sliding move 7 ment of-the pin will be limited. By withi from the groove the pin can be removed.

What is claimed is: I

,LAn instrument of the class described including a'semi-circular protractor head having a zero graduation at the center of its arcuat-e edge, the straight edge of the head being cut away at its center to provide a clearance, anarm detachably connected to the head and having a straight edgein line with the zero graduation and the center of the straight edge of the head, a bracket fixedly secured to the head and overhanging the clearance, and a centering pin carried by the bracket and, extending through said clear- I ance forengaging a supporting surfaceat a point in line with the zero graduation and the straightedge of the arm, said arm" being "removable from the head without disturbingitheipin;-

'2'. An instrument of the class" described in eluding a protractor head having its arcuate edge graduated to indicate all of the degrees of a circle, the "Zero graduationsbeing lo cated at the center of said edge, said head being semi-circular and having a straight graduated edge'provided witha central clearance, a graduated'arin extending from the straight edge of the head and having one edge substantially in line with the center of "said:

straight edge and withthe Zerograduation, 'the'straight edge ofsaid arm being cutaway to providea clearance adapted to register with theclearance in thestrai ght edge of the head, a bracket fixedly connected tothe head and overlying the registering clearances, and

acenterin'g pin movably connected to the bracket and insertable into the clearances to. engage a supporting surface at a point in line with the straight edge of the head, and

means for detachably securing saidarm to the r head for removal without. disturbing thepin and its bracket. v p ,p ,i .7 In testimonythat Iclaim theiforegoing as my own, I have hereto aflixed my si-gnature.

CHARLES reoLD uf 

